1. Field of the Invention
Embodiments of the present invention relate generally to processor extensions and, more particularly, to processor extensions for accelerating a spectral band replication.
2. Background Art
Low bitrate audio coding using conventional perceptual audio codecs is not possible without significant degradation of audio quality. Spectral Band Replication (SBR) is a high frequency reconstruction technique that improves the quality of low bitrate audio. SBR also improves the performance of narrow band speech codecs by improving speech quality, speech intelligibility and speech comprehension.
In SBR, high frequency components of an audio signal are coded in an efficient manner. The conventional perceptual audio codec is responsible for coding the lower part of the spectrum. Guidance information (i.e., SBR data) regarding the high frequency components of the audio signal and the coded low frequency components are transmitted. An SBR decoder at the receiver regenerates the higher frequencies based on the guidance information and an analysis of the lower frequencies transmitted in the underlying coder. Subsequently, the SBR decoder regenerates the audio signal by synthesizing the low and high frequency components.
SBR is efficient for harmonic or noise-like components and allows for proper shaping in the time domain as well as in the frequency domain. As a result, SBR allows full bandwidth audio coding at very low data rates, thus offering a significantly increased compression efficiency compared to the core coder.
Unfortunately, the process of SBR decoding in the prior art to regenerate the audio signal can be computationally expensive and results in increased computational complexity of the decoder. The increase in computational complexity results in increased power dissipation which can be a particular problem in mobile platforms.